Mercurial > hg > graal-compiler
view src/share/vm/memory/heap.hpp @ 452:00b023ae2d78
6722113: CMS: Incorrect overflow handling during precleaning of Reference lists
Summary: When we encounter marking stack overflow during precleaning of Reference lists, we were using the overflow list mechanism, which can cause problems on account of mutating the mark word of the header because of conflicts with mutator accesses and updates of that field. Instead we should use the usual mechanism for overflow handling in concurrent phases, namely dirtying of the card on which the overflowed object lies. Since precleaning effectively does a form of discovered list processing, albeit with discovery enabled, we needed to adjust some code to be correct in the face of interleaved processing and discovery.
Reviewed-by: apetrusenko, jcoomes
author | ysr |
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date | Thu, 20 Nov 2008 12:27:41 -0800 |
parents | a61af66fc99e |
children | c18cbe5936b8 |
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/* * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ // Blocks class HeapBlock VALUE_OBJ_CLASS_SPEC { friend class VMStructs; public: struct Header { size_t _length; // the length in segments bool _used; // Used bit }; protected: union { Header _header; int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ]; // pad to 0 mod 8 }; public: // Initialization void initialize(size_t length) { _header._length = length; set_used(); } // Accessors void* allocated_space() const { return (void*)(this + 1); } size_t length() const { return _header._length; } // Used/free void set_used() { _header._used = true; } void set_free() { _header._used = false; } bool free() { return !_header._used; } }; class FreeBlock: public HeapBlock { friend class VMStructs; protected: FreeBlock* _link; public: // Initialization void initialize(size_t length) { HeapBlock::initialize(length); _link= NULL; } // Merging void set_length(size_t l) { _header._length = l; } // Accessors FreeBlock* link() const { return _link; } void set_link(FreeBlock* link) { _link = link; } }; class CodeHeap : public CHeapObj { friend class VMStructs; private: VirtualSpace _memory; // the memory holding the blocks VirtualSpace _segmap; // the memory holding the segment map size_t _number_of_committed_segments; size_t _number_of_reserved_segments; size_t _segment_size; int _log2_segment_size; size_t _next_segment; FreeBlock* _freelist; size_t _free_segments; // No. of segments in freelist // Helper functions size_t number_of_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; } size_t size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; } size_t segment_for(void* p) const { return ((char*)p - _memory.low()) >> _log2_segment_size; } HeapBlock* block_at(size_t i) const { return (HeapBlock*)(_memory.low() + (i << _log2_segment_size)); } void mark_segmap_as_free(size_t beg, size_t end); void mark_segmap_as_used(size_t beg, size_t end); // Freelist management helpers FreeBlock* following_block(FreeBlock *b); void insert_after(FreeBlock* a, FreeBlock* b); void merge_right (FreeBlock* a); // Toplevel freelist management void add_to_freelist(HeapBlock *b); FreeBlock* search_freelist(size_t length); // Iteration helpers void* next_free(HeapBlock* b) const; HeapBlock* first_block() const; HeapBlock* next_block(HeapBlock* b) const; HeapBlock* block_start(void* p) const; // to perform additional actions on creation of executable code void on_code_mapping(char* base, size_t size); public: CodeHeap(); // Heap extents bool reserve(size_t reserved_size, size_t committed_size, size_t segment_size); void release(); // releases all allocated memory bool expand_by(size_t size); // expands commited memory by size void shrink_by(size_t size); // shrinks commited memory by size void clear(); // clears all heap contents // Memory allocation void* allocate (size_t size); // allocates a block of size or returns NULL void deallocate(void* p); // deallocates a block // Attributes void* begin() const { return _memory.low (); } void* end() const { return _memory.high(); } bool contains(void* p) const { return begin() <= p && p < end(); } void* find_start(void* p) const; // returns the block containing p or NULL size_t alignment_unit() const; // alignment of any block size_t alignment_offset() const; // offset of first byte of any block, within the enclosing alignment unit static size_t header_size(); // returns the header size for each heap block // Returns reserved area high and low addresses char *low_boundary() const { return _memory.low_boundary (); } char *high_boundary() const { return _memory.high_boundary(); } // Iteration // returns the first block or NULL void* first() const { return next_free(first_block()); } // returns the next block given a block p or NULL void* next(void* p) const { return next_free(next_block(block_start(p))); } // Statistics size_t capacity() const; size_t max_capacity() const; size_t allocated_capacity() const; size_t unallocated_capacity() const { return max_capacity() - allocated_capacity(); } // Debugging void verify(); void print() PRODUCT_RETURN; };